CN108959677A - The optimal multiple grounding number calculating method of power distribution network TN-C earthed system - Google Patents
The optimal multiple grounding number calculating method of power distribution network TN-C earthed system Download PDFInfo
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- CN108959677A CN108959677A CN201810212074.XA CN201810212074A CN108959677A CN 108959677 A CN108959677 A CN 108959677A CN 201810212074 A CN201810212074 A CN 201810212074A CN 108959677 A CN108959677 A CN 108959677A
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- grounding
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Abstract
The present invention provides a kind of optimal multiple grounding number calculating method of power distribution network TN-C earthed system, it include the following steps: (1) the multiple grounding for TN-C earthed system, to be grounded the minimum target of cost, to be grounded number as optimized variable, the Optimized model for calculating optimal ground connection quantity is provided；Step 2, the derivation algorithm for providing Optimized model.Present invention primarily contemplates ground fault scenes, and in the case of considering that grounding point is uniformly distributed, and for the multiple grounding of TN-C earthed system, provide the model and algorithm for calculating optimal multiple grounding point quantity, and then being formed can be with the calculation method of Guiding Practice.
Description
Technical field
The present invention relates to electrical system field more particularly to a kind of optimal multiple grounding number meters of power distribution network TN-C earthed system
Calculation method.
Background technique
Low-voltage network is the end system powered to huge numbers of families, and is related to that face is most wide, can most cause user equipment
The power supply system of damage and human casualty accident.For power supply and security needs, it is a very heavy that how low-pressure system, which is grounded,
The problem of wanting, as ground connection type selecting it is improper or low-pressure system occur ground fault post-processing it is improper and caused by the person or equipment
Accident happens occasionally, so analysing in depth, solving the problems, such as that the related ground connection aspect of low-pressure system has a very important significance.
There are mainly three types of low-voltage ground system earth patterns, i.e. TN earthed system, TT earthed system and IT earthed system.Its
In, TN earthed system can be divided into TN-C earthed system, TN- according to the configuration mode of working zero line (N) and protection zero line (PE)
C-S earthed system and TN-S earthed system.
20 middle of century, the Grounding Types of former Soviet Union's low-voltage distribution system are substantially all using TN-C earthed system.Although
TN-C earthed system can save a PE line compared with TN-S earthed system, but in protective earthing-neutral conductor broken string, since overcurrent protection cannot
Movement, the very high contact voltage of electric leakage equipment long-term existence be easy to cause shock hazard.It is external in recent years also to being mounted with to remain
The issuable harm of low voltage electric network in the case of aftercurrent protector is studied, it is noted that after being mounted with earth leakage protective device
Equipment can still generate the case where contact voltage when failure.
Foreign countries also improve TN-C earthed system while using TN-S earthed system, into building after adopt
With TN-C-S earthed system, in order to reduce contact voltage when protective earthing-neutral conductor broken string, by its multiple grounding at building entrance.Beauty
State uses always multiple grounding TN-C-S earthed system.This multiple grounding TN-C-S earthed system is also referred to as multiple spot and protected by Britain
Earthed system is protected, it is more and more common at present to be applied to new architectural power supply.In the application of external TN-C-S earthed system in recent years,
Although the contact voltage generated when protective earthing-neutral conductor broken string can be effectively reduced in TN-C-S earthed system, need to increase a conducting wire
Investment, improves cost.
In order to integrate with IEC standard, electrical security is improved, in the phase at the end of the nineties in last century, Russia is proposed 1995
Year pervious low-voltage network is transformed into TN-S earthed system from TN-C earthed system, but need millions of kilometers conducting wire and
Cable, it is therefore proposed that modification former Soviet Union specification, no matter overhead transmission line or cable run power supply, TN-C earthed system is in user entry
Place must carry out multiple grounding.It can not be achieved the current potential of protection conductor in such as skyscraper heavy construction as closely as possible
, can be using the sub-surface conductors of generic equivalent-potential bonding in building as multiple grounding body when current potential, this multiple grounding TN-C connects
The electrical security level of ground system is poor unlike TN-S earthed system, therefore is generally used in foreign countries, but IEC standard is not
There are the grounding resistance and earthing position of clear stipulaties multiple grounding, it is safe for multiple grounding and economy reasonable still to lack
Change Research on configuration.
In China, electricity supply and use equipment when due to the seventies is poor, in addition management level falls behind, causes person electric shock injures and deaths thing
Therefore happen occasionally, therefore, country is to promote the use of voltage-type protector, this guarantor in rural area at first for the protection of low-voltage circuit
The method of operation that device is suitable for distribution transformer isolated neutral is protected, so rural low voltage network is at the end of the seventies to the eighties
Just the method for operation of the low-pressure side neutral point through high resistance ground, i.e. " rural area low tension are all changed to for installation voltage-type electric protective device
Power technical regulation " meaning IT earthed system.Part document also describes some applications of IT earthed system.
Through operation in a few years, isolated neutral system cannot limit low voltage electric network for some reason caused by it is right
Ground high voltage, such as Lightning Over-voltage, switching overvoltage, high- and low-voltage circuit joint use induced overvoltage.Neutral point high resistant connects
In ground system, due to a certain phase line Leaked Current of Line to Ground, so that its phase line-to-earth voltage is increased to line voltage, zero curve pair is measured in maintenance
Ground is with voltage, and the phenomenon that a certain relatively no-voltage.Although voltage-type protector at that time plays reduction electric shock casualty accident
No small protective effect, but since that there is operational percentages is low for it, protection reliability is poor, can not fill branch protection and operation of power networks
On it is equal the defects of, so being substituted by current mode protector rapidly in the eighties.
From the foregoing, it can be seen that the method for operation of China's low voltage electric network be the eighties adapt to earth leakage protective device service requirement and
Change.Currently, all oneself reaches a kind of horizontal to most of electric power facility, the power supply facilities in rural area after rural power grids are engineered
Health status be not less than city, can the Grounding Types for using TN-C earthed system same as urban distribution network.
The advantages of TN-C earthed system is that protective earthing-neutral conductor has PE line and N line function concurrently, can save a conducting wire, while also can be used
Overcurrent protection also serves as the protection of electrical equipment insulation fault.The disadvantage is that fault current can pass through if ground short circuit failure occurs for system
The working earthing of the people and transformer that touch electric leakage equipment constitute circuit, cause directly to human body using threat.In order to solve
The above problem, main solution at this stage is multiple grounding.
In terms of existing research conditions, most of article refers to and analyzes the effect and importance of multiple grounding, document
(Guo builds harm and prevention [J] the Shanghai University Of Electric Power journal of military distribution network system mesolow system zero-line failure, 2015,31 (z1):
The approximate location and resistance value of calculating multiple grounding 99-101.) proposed, but the document is for the case where giving resistance value
Under, how to provide optimal multiple grounding quantity and does not refer to；Document is (slowly electric with multiple grounding in raw electrical engineering and always etc.
Position is coupled measure to quantitative analysis [J] the electric power journal for reducing human contact's voltage, 2004,04:309-310+315.) demonstration
Multiple grounding and equipotential bonding are matched to the importance for reducing fault contact voltage；Document (Li Yingchun, Zhang Wanming .TN
Selection [J] Chinese science and technology information of the effect of PE (PEN) line multiple grounding and its resistance value in system, 2006,17:98-100+
103.) it proposes to guarantee fail-safe voltage in 50V hereinafter, it is 10 that the resistance value of multiple grounding, which should not be simply provided,
Ω, but whether article only has effect with Equivalent Circuit multiple grounding, does not provide specific multiple grounding position
And resistance value size.Document (is grounded the analysis with zero connection protection and applies the Hunan [J] science and engineering in Wu Shu duckweed low-voltage distribution system
Institute's journal (natural science edition), 2014,03:49-53.) analyze the office being grounded in low-voltage network system with zero connection protection
It is sex-limited, the solution of multiple grounding is proposed, but do not propose specific solution.It can be seen that TN-C earthed system connects
The multiple grounding Research on configuration of ground pattern is started to walk, but specific configuration scheme does not refer to also.
The major defect of the prior art is not provide optimal multiple grounding quantity, therefore, takes how many place's ground connection actually,
This fully relies on experience or exploration in practice, and does not provide the analysis of quantization and compare.
Term is explained:
IT earthed system: mains neutral point is earth-free, or through high resistance grounding, and the exposed of load side electrical equipment is led
Electric part is directly grounded through respective protection zero line, the mutually independent earthed system of ground connection with source side.
TT earthed system: mains neutral point be directly connected to, and the exposed conductive part of load side electric device connects
Earthed system onto the independent grounding device unrelated with electric system grounding point.
TN earthed system: mains neutral point ground connection and draws the neutral conductor, the exposed conductive part of electrical equipment directly with
The neutral conductor is connected.
TN-C earthed system: the earthed system of working zero line N and protection zero line PE unification.
TN-S earthed system: working zero line N and protection zero line PE separated earthed system.
TN-C-S earthed system: whole system main line part protection zero line (PE) is unification, branch line with working zero line (N)
Rear portion divides protection zero line (PE) with working zero line (N) to be the earthed system separated.
Summary of the invention
The technical problem to be solved in the present invention is to provide a kind of optimal multiple grounding number meter of power distribution network TN-C earthed system
Calculation method, it is main to consider ground fault scene, and in the case of considering that grounding point is uniformly distributed, for TN-C earthed system
Multiple grounding provides the model and algorithm for calculating optimal multiple grounding point quantity, and then being formed can be with the calculating of Guiding Practice
Method.
Problem of the invention is achieved in that
A kind of optimal multiple grounding number calculating method of power distribution network TN-C earthed system, includes the following steps:
Step 1, for the multiple grounding of TN-C earthed system, to be grounded the minimum target of cost, be grounded number for optimization
Variable provides the Optimized model for calculating optimal ground connection quantity；Specifically:
If TN-C earthed system uses multiple grounding, shares and be used as grounding point at x, and grounding point is uniformly distributed, if often
The investment of a set of earthing or grounding means is c, then the cost C (x) being grounded is indicated are as follows:
C (x)=cx (1)
To be grounded cost minimization as the target of optimization, then the objective function optimized is expressed as；
Min C (x)=cx (2)
In formula (2), minC (x) expression is minimized the cost C (x) of ground connection, and c indicates the throwing of every suit earthing or grounding means
Money, x indicate the quantity of grounding point；
If ground fault occurs for TN-C earthed system, the contact voltage on electrical equipment shell is U (x), then U (x) is answered
Meet safe voltage U required in practices, it may be assumed that
U(x)≤Us (3)
Formula (3) gives the constraint relationships such as not being grounded in quantity optimization, and the U (x) in formula (3) is connect in TN-C
When ground fault occurs for ground system, according to the structure of power grid, the parameter of each element in network utilizes the constraint of circuit and symmetrical point
The parameter that amount method provides；The Optimized model for providing the optimal ground connection quantity of calculating is as follows:
Formula (4) contains the condition of an objective function and an inequality constraints；
Step 2, the derivation algorithm for providing Optimized model: defining penalty according to the Optimized model that formula (4) provides, and calculates
The quantity x of the cost C (x) that is grounded out and grounding point when C (x) being made to reach minimum value.
Further, in the step 2, the cost of ground connection is calculated using the hybrid algorithm of comprehensive interior point method and outer point method
The quantity x of C (x) and grounding point when C (x) being made to reach minimum value；When specifically solving the Optimized model, U in formula (4)
(x) calculating is the actual circuit model according to TN-C earthed system, and is calculated using symmetrical component method.
Further, after the step 2 further include:
Step 3 prepares a computer program according to the Optimized model and derivation algorithm that provide.
The present invention has the advantages that present invention primarily contemplates ground fault scenes, and considering that grounding point is equally distributed
Under situation, for the multiple grounding of TN-C earthed system, to be grounded the minimum target of cost, to be grounded number as optimized variable, give
The Optimized model and algorithm of optimal ground connection quantity are calculated out, and then provides its complete calculation method, and the system of calculating takes more
Place's grounding point is only optimal less, can be provided the quantity of the multiple grounding point of TN-C earthed system in an optimal manner, be can be used to
The actual implementation of TN-C system multiple grounding is instructed in help.
Detailed description of the invention
The present invention is further illustrated in conjunction with the embodiments with reference to the accompanying drawings.
Fig. 1 is a kind of execution flow chart of the optimal multiple grounding number calculating method of power distribution network TN-C earthed system of the present invention.
Specific embodiment
To be clearer and more comprehensible the present invention, now with a preferred embodiment, and attached drawing is cooperated to be described in detail below.
As shown in Figure 1, the optimal multiple grounding number calculating method of a kind of power distribution network TN-C earthed system of the invention, is mainly examined
Ground fault scene is considered, and in the case of considering that grounding point is uniformly distributed, for the multiple grounding of TN-C earthed system, to connect
Cost minimum target in ground provides the Optimized model for calculating optimal ground connection quantity, and propose to optimize to be grounded number as optimized variable
The derivation algorithm of model ultimately forms a set of method for calculating optimal ground connection quantity；Specifically comprise the following steps:
Step 1, for the multiple grounding of TN-C earthed system, to be grounded the minimum target of cost, be grounded number for optimization
Variable provides the Optimized model for calculating optimal ground connection quantity；Specifically:
If TN-C earthed system uses multiple grounding, shares and be used as grounding point at x, and grounding point is uniformly distributed, if often
The investment of a set of earthing or grounding means is c, then the cost C (x) being grounded is indicated are as follows:
C (x)=cx (1)
To be grounded cost minimization as the target of optimization, then the objective function optimized is expressed as；
Min C (x)=cx (2)
In formula (2), minC (x) expression is minimized the cost C (x) of ground connection, and c indicates the throwing of every suit earthing or grounding means
Money, x indicate the quantity of grounding point；
If ground fault occurs for TN-C earthed system, the contact voltage on electrical equipment shell is U (x), then U (x) is answered
Meet safe voltage U required in practices, it may be assumed that
U(x)≤Us (3)
Formula (3) gives the constraint relationships such as not being grounded in quantity optimization, and the U (x) in formula (3) is connect in TN-C
When ground fault occurs for ground system, according to the structure of power grid, the parameter of each element in network utilizes the constraint of circuit and symmetrical point
The parameter that amount method provides；The Optimized model for providing the optimal ground connection quantity of calculating is as follows:
Formula (4) contains the condition of an objective function and an inequality constraints；
Step 2, the derivation algorithm for providing Optimized model: penalty is defined according to the Optimized model that formula (4) provides, and is adopted
When being calculated the cost C (x) of ground connection with the hybrid algorithm of comprehensive interior point method and outer point method and C (x) is made to reach minimum value
The quantity x of grounding point；When specifically solving the Optimized model, the calculating of U (x) is the reality according to TN-C earthed system in formula (4)
Border circuit model, and calculated using symmetrical component method；
Step 3, using other high-level languages such as C language or Matlab, according to provide Optimized model, penalty form
Prepare a computer program (software) with derivation algorithm, software be it is general, when operation, as long as input contains system structure and parameter
Data；The establishment of software only needs common PC machine or laptop, as long as being configured with the volume of relevant high-level language
Release system is translated or solved, special system and device is not needed.
Advantages of the present invention is as follows:
Present invention primarily contemplates ground fault scenes, and in the case of considering that grounding point is uniformly distributed, connect for TN-C
The multiple grounding of ground system, to be grounded number as optimized variable, provides to be grounded the minimum target of cost and calculates optimal ground connection number
The Optimized model and algorithm of amount, and then its complete calculation method is provided, it is optimal that the system of calculating takes how many place's grounding points to be only
, the quantity of the multiple grounding point of TN-C earthed system can be provided in an optimal manner, can be used to help to instruct TN-C system weight
The actual implementation on multiple connection ground.
Although specific embodiments of the present invention have been described above, those familiar with the art should be managed
Solution, we are merely exemplary described specific embodiment, rather than for the restriction to the scope of the present invention, it is familiar with this
The technical staff in field should be covered of the invention according to modification and variation equivalent made by spirit of the invention
In scope of the claimed protection.
Claims (3)
1. a kind of optimal multiple grounding number calculating method of power distribution network TN-C earthed system, characterized by the following steps:
Step 1, for the multiple grounding of TN-C earthed system, to be grounded the minimum target of cost, to be grounded number as optimized variable,
Provide the Optimized model for calculating optimal ground connection quantity；Specifically:
If TN-C earthed system uses multiple grounding, shares and be used as grounding point at x, and grounding point is uniformly distributed, if every suit
The investment of earthing or grounding means is c, then the cost C (x) being grounded is indicated are as follows:
C (x)=cx (1)
To be grounded cost minimization as the target of optimization, then the objective function optimized is expressed as；
Min C (x)=cx (2)
In formula (2), minC (x) expression is minimized the cost C (x) of ground connection, and c indicates the investment of every suit earthing or grounding means, x table
Show the quantity of grounding point；
If ground fault occurs for TN-C earthed system, the contact voltage on electrical equipment shell is U (x), then U (x) should meet
Required safe voltage U in practices, it may be assumed that
U(x)≤Us (3)
Formula (3) gives the constraint relationships such as not being grounded in quantity optimization, and the U (x) in formula (3) is to be grounded to be in TN-C
When ground fault occurs for system, according to the structure of power grid, the parameter of each element in network, constraint and symmetrical component method using circuit
The parameter provided；The Optimized model for providing the optimal ground connection quantity of calculating is as follows:
Formula (4) contains the condition of an objective function and an inequality constraints；
Step 2, the derivation algorithm for providing Optimized model: penalty is defined according to the Optimized model that formula (4) provides, calculates and connects
The quantity x of the cost C (x) on ground and grounding point when C (x) being made to reach minimum value.
2. a kind of optimal multiple grounding number calculating method of power distribution network TN-C earthed system as described in claim 1, feature exist
In: in the step 2, the cost C (x) of ground connection is calculated using the hybrid algorithm of comprehensive interior point method and outer point method and makes C
(x) the quantity x of grounding point when reaching minimum value；When specifically solving the Optimized model, the calculating of U (x) is basis in formula (4)
The actual circuit model of TN-C earthed system, and calculated using symmetrical component method.
3. a kind of optimal multiple grounding number calculating method of power distribution network TN-C earthed system as described in claim 1, feature exist
In: after the step 2 further include:
Step 3 prepares a computer program according to the Optimized model and derivation algorithm that provide.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN110188319A (en) * | 2019-05-31 | 2019-08-30 | 福建工程学院 | TN-C system earth quantity computation method based on multiple-objection optimization |
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| CN1261733A (en) * | 2000-02-02 | 2000-08-02 | 机械工业部设计研究院 | Earthing protective method and device for low voltage distribution system |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN110188319A (en) * | 2019-05-31 | 2019-08-30 | 福建工程学院 | TN-C system earth quantity computation method based on multiple-objection optimization |
| CN110188319B (en) * | 2019-05-31 | 2022-10-21 | 福建工程学院 | Method for calculating number of grounding points of TN-C grounding system based on multi-objective optimization |
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